Currently, an LDP-NR is created whenever:
a) content-type of a POST or PUT request is not RDF
b) Content-Disposition: attachment header is present
At present, this is not codified in the specification draft doc:
The LDP spec is fairly silent about when a repository should create an LDP-NR. This ticket is to see if there is a better way (possibly leveraging LDP headers) to explicitly convey a client's intent that a given resource should be created as a LDP-NR, and incorporate the conclusion into the spec draft.
A case to consider is persisting an arbitrary RDF document (e.g. an owl document, RDF-based dataset, etc) as a binary resource in Fedora with an rdf media type. This case precludes (a) from the above techniques for specifying binary resource creation.
See discussion in https://github.com/fcrepo4/fcrepo4/pull/1081